1. Field of the Invention
The present invention relates to an ophthalmic apparatus for photographing a retroillumination image or a sectional image of an anterior part of an eye to be examined.
2. Description of Related Art
Conventionally, there are two major ways to evaluate cataract. One is to project illumination light through a pupil of an eye to be examined. The scattered light from a fundus of the eye illuminates a crystalline lens and thereby observing a retroillumination image of the crystalline lens from the front. This manner enables to observe development of cataract throughout the crystalline lens.
The other is to optically cut the eye to be examined by slit light and then observe an anterior part of the eye by a photographing optical system arranged in accordance with the Scheimpflug's principle. This manner allows to obtain location of an opaque area in the crystalline lens and degree of its opacity.
Suggested in consideration of the above is an apparatus which is capable of photographing both a retroillumination image as well as a sectional image of the anterior part of the eye. When utilizing this type of apparatus, an irradiation system and a photographing system are switched upon photographing a retroillumination image and photographing a sectional image.
In a conventional apparatus, however, there is no correlation between the retroillumination photography and the sectional image photography and thus it is left to an examiner's judgement. That is to say, the examiner decides a rotation angle at which the section of the anterior part of the eye is to be photographed entirely depending on his intuition and experience. Therefore, there may be cases where a required picture image can not be obtained or photography has to be repeated over and over, which imposes excessive burden on the examinee.